Amends the California Constitution to provide that only marriage between one man and one woman is valid or recognized in California, whether contracted in this state or elsewhere. Voids and restricts registered domestic partner rights and obligations, for certain same-sex and heterosexual couples, in areas such as: ownership and transfer of property, inheritance, adoption, medical decisions, child custody and child support, health and death benefits, insurance benefits, hospital visitation, employment benefits, and recovery for wrongful death and other tort remedies. Summary of estimate by Legislative Analyst and Director of Finance of fiscal impact on state and local governments: Unknown, but probably not significant, fiscal effect on state and local governments. The impact would depend in large part on future court interpretations.